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The Steganography is a fascinating technique for hiding one form of information inside another file. The benefit of using this type of hiding is no evidence are provided to prove that the information is concealed (Mansfield and Antonakos, 2009). The method of cryptography is to secure the data in existing application. Cryptography is the method of coding the data and directing it to receiver there by providing the security in the network. Steganography uses the encryption as well as decryption techniques of cryptography using certain algorithms. The threat of an intruder accessing secret information has been an ever existing concern for the data communication experts. Cryptography and steganography are the most widely used techniques to overcome this threat (Marwaha and Marwaha, 2010). Image steganography is a mechanism of covering the text messages in an external image file. While receiving the information, the receiver can view only the image and the data will not be exposed to them. The existing system can extracts the text information from the image file. The system possesses several complexities while sending large data files to the destination part. According to Cheddad et al (2010), quality of the image gets diminished in the image steganography technique. This decreases the possibility of handling huge information between the sender and receiver in the existing system. Joan Cabestany (2009) mentioned that the large size file or any external file formats cannot be embedded inside the image file in the simple image steganography system. The need of a highly secure system to transfer information over any communication media minimizing the threat of intrusion lead to development of proposed system. Text steganography is also an existing method of hiding information. Since the file size of the secret data which can be embedded is limited, the system is found to be not efficient than the image steganography which also hides some text information.
Kale et al (2008) explains different aspects to be considered during hiding information using image Steganography are security, capacity and robustness. The current system uses only JPEG, GIF and BMP file for hiding the messages. This uses a method of replacing the least significant bits or LSB of pixel in the image with message to be covered (Liu et al, 2007). The LSB contributes only very small part of the image and its substitution may not cause more effect on the image. The existing system performs general encryption algorithm for performing encryption operation. As per Bandyopadhyay (2008), the image can be compressed using a zip format. The image compression after the encryption may also minimize quality of image. During extraction phase of the existing system, the secret message will be extracted from the steganography image using the same password provided at the time of encryption.
The encrypted message or the original one is attached as secret message to the graphic image file. The resulted image produced is known as stego image. Extra secret information used for concealing the data is the stego key. The steganography image is then moved to the recipient side. The receiver retrieves the information from the carrier image. Only person knowing the secret information of key is able to extract those messages. For this secret key is distributed among sender and the recipient. (Shandilya and Tiwari, 2010). Reliability of data transferred between sender and the destination is able to analyze by using the image steganography. This process also finds out any changes occurred in the steganography image.(Babu et al, 2009).
The traditional systems have certain limitations. The system can conceal only some kind of text files. The size of the data appended is also limited to particular extent. There are difficulties in embedding audio as well as video files in an image file in case of present system. As per Sajedi and Jamzad (2010), the system can only insert text file and have a low information handling capacity. The distortion in the quality of the image is the other problem that occurs during the process. The resolution of the displaying image is decreased which results in a very low quality image at the receiver side. Thus the existing system places a boundary in embedding information as well as it affect the clarity of the image. Both these techniques provide some security of data neither of them alone is secure enough for sharing information over an unsecure communication channel and are vulnerable to intruder attacks.
The information hiding using steganoraphy make use of the LSB concept of concealing the information in a secured manner. But the scan lines of image containing the binary data are altered along with the sequential modification in LSB of each pixel. Only the image part where the secret information is stored is changed according to the requirements. An expert hacker is able to extract the information easily. The network hacker will continuously repeat the network hacking process in order to retrieve the information. So the security of the data cannot be assured. The approach of modifying the master image alters the overall image property and it increases the chances of being attacked by the intruder since they can easily detect the distorted image. The quality of the image is reduced and which is helpful for the intruder to attack the network. Pachghare (2009), states that it needs a lot of operating cost to hide a little bit of information. Once the intruder identifies the system, it becomes virtually worthless to use the system.
According to Changder et al (2010), text Steganography hide the secret message in the text by creating meaningful sentences after finding the longest common subsequence of two binary string among which one is the secret message and another may be any binary string. If document is digital, any modern word processor would be able to show spacing irregularities or worse reformat the document and destroy the hidden information. The inability to transmit large information limits its practicality.
The first letter algorithm used in text Steganography is not very secure, since the person having knowledge of the system can easily find the secret message. The requirements for imperceptibility of algorithm in Steganography are invisibility of the algorithm, payload capacity, robustness, independence of file format and unsuspicious files (Bandyopadhyay, 2008). A method of hiding secret information in each nth letter of all the words of text data is done in text Steganography. This type is not a permanent method of achieving security during the transfer of data. This causes the development of proposed system.
The proposed system overcomes the disadvantages of the existing one by storing large amount of data in the external file to be covered. In the traditional system, the data hiding is done by using only the image file. But the current system uses video files to cover the data. Large files of some MB size can be attached in the video files without affecting the quality of the video. The data encryption occurs and the data is secured in an efficient way without losing the clarity. The proposed system offers the storage of large size files in a video file and displays it without losing the video quality. The possibility of attack by an intruder is very low in this system since there is no sign of data encryption anywhere in the image. The different module in the proposed system includes hiding files, hiding text messages, retrieving files and retrieving messages. The Data Encryption Standard algorithm technique is used for securing data. The encrypted message is always in byte format. It is embedded in master video file in an array. The retrieving of data is done in the retrieving module without causing any distortion to the quality of the image. The procedure adopted in the proposed system is the evaluation for image and video Steganography since video Steganography is the combination of image and audio Steganography (Bandyopadhyay, 2008). This is a new definition to implement the security in the data communication process. The developed system is a desktop application which uses JDK 1.7 as the programming language for the development of software. The system can be developed using Windows XP as operating system.
An external master file will form a new byte of array. The encrypted information is also stored in an array. This secret message in the array will be embedded in to master file array and the resulted file is produced. The output information is a normal video file which is encrypted with the secret message. The data communication occurs through Email, LAN, file upload in internet etc in which the output file is moved to the destination. The encrypted file cannot be viewed to the hacker who is trying to attack the system. This is the advantage of the proposed system.